There have been a lot of projections from both sides in the EU referendum campaign about what a Britain outside the EU would look like. Many of them are looking at the longer term. But what would actually happen, on June 24, the day after the referendum, if the British public voted to leave the EU?

In this extract from the second episode of The Anthill, a podcast from The Conversation UK, our education and society editor Gemma Ware talks to Anand Menon, professor of European politics and foreign affairs at King’s College London and director of the UK in a Changing Europe initiative.

Interview with Anand Menon, professor of European politics at King’s College London.
The Anthill, CC BY-ND3.61 MB(download)

What would actually happen on June 24, the day after a Brexit?

If the UK votes to leave, several things will happen quite quickly. I suspect that (the prime minister) David Cameron will have to think about when to resign because I don’t think his position will be tenable after the country has voted against a proposition that he has defended so strongly up and down the country. Whether he goes immediately or not, it’s hard to say, because there might be a case for him to stay in place and for him to start the initial negotiations with the other EU member states. The combined uncertainty of having voted to leave and having to choose a prime minister all at the same time would have very very serious implications for the country.

What I don’t think will happen is what we used to call the “Boris scenario” before Boris (Johnson) committed himself to the leave side. According to this, we would vote to leave, everyone would go “oh my god”, we’d go and talk to our European partners, they’d offer us a few concessions and then we’d vote again and decide to stay. I don’t think there’s any possibility of having a second vote, simply for political reasons.

So, we’re talking about a glide path towards leaving and this will include us talking to our partners to decide when we trigger Article 50 (the law that governs exiting the EU). I’m sure that the other EU member states, once we’ve taken this decision, will be keen to get it sorted out as soon as possible. So I don’t think they’ll be very patient and will want us to wait too long before invoking Article 50.

What about EU citizens living in the UK or UK citizens living in the EU? Are they going to have to make plans pretty quickly?

Well no. There are several things here. One, Article 50 negotiations will take two years and they might take more, and nothing happens until those negotiations are out of the way. So there will be a long grace period of at least two years and possibly longer. Second, I find it inconceivable that either side will think “let’s come to a deal where we have to start deporting people already in place”.

The leave camp have intimated that this is not what they’d be seeking to do: people who are already here would be safe. I know that the Spanish prime minister has been making noises about the Brits currently in Spain. My response to that would be: well he would say that, wouldn’t he because he wants us to vote to stay. So I think that anything that other heads of state or governments say should be treated with a pinch of salt because they’re angling for a certain outcome.

My guess is, both for practical reasons, out of humanity if you like, and because of some residual rights under international law, that in fact, people currently resident in another EU state of which they are not a citizen, will be fine.

What happens if it’s very, very close?

A very, very close vote to leave on the back of a low turnout would I think still be fatal for David Cameron, but it might I suppose open up a little bit of space for whoever replaces him to say “look, this was very close I’m going to go back and do it again”. I still think that politically it’s problematic because so many of the people who want us to leave the EU have regularly criticised the EU for it’s readiness to re-run referenda in other countries. It puts them in a very delicate political situation to try that here.

If it’s a remain vote, will there be a big sigh of relief across Europe or will there be other ramifications?

Let me say three things about that. The first is that margin is crucial. If we vote by 70-30 to stay then actually that changes everything and we’ve committed our future to the European Union. (Second), if it’s a narrow vote, if it’s again the 51-49 on a low turnout, then we can expect the leavers to say “it was rigged, we need to do it again”, and if it’s close I suspect the political pressure to do this again will be immense and in the next few years we will.

The third thing I would say is that even if we vote to stay in by a significant margin, Britain will not become a normal, nice, constructive EU member. If we vote to stay in, we’ll vote grudgingly, bad-temperedly, in a sullen kind of “don’t like the EU but it all sounds a bit frightening to leave” kind of way, which means that none of the political problems around our membership, either in the general public or in the Conservative Party will have been resolved and actually we’ll almost be back to square one.